Cosmology Question

If a galaxy has a luminosity of 6.6x10^39 W and a brightness measured as 1.25x10^-11 W m^-2, How far away is the galaxy in mega parsecs?

An absorption line of the element beryllium is observed in the spectrum of the galaxy aboveas lying 509.4 nm. What is the speed of the recession of teh galaxy in km s^1 assuming that the speed of light is c = 3.00 x 10^5 km s^-1

And what is the value of the hubble constant?